Halogen substituted dialkylaminoacylanilides

ABSTRACT

New dialkylaminoacylanilides substituted with a halogen atom in the dialkylamino group are disclosed which are useful as local anesthetics.

United States Patent 91 Ross et al. Apr. 8, 1975 [5 HALOGEN SUBSTITUTED [58] Field of Search; 260/562 DIALKYLAMINOACYLANILIDES [75] Inventors: Svante Bertil Ross, Sodertalje; Rune [56] r I References and Verner Sandberg, Jarna; Berndt OTHER PUBLICATIONS Harald j 'gi Sven Bengt Beksha et al., J. Org. Chem. USSR, Vol. 1 pp. Arvid Akerman, both of Sodertalje, 1373-]g78 (i9 6 5) of Sweden Blatt, Organie Synthesis, Collective Vol. ll, pp. 91-93 I [73] Assignee: Aktiebolaget Astra, Sodertalje, (1943) Sweden Primary Examinerl-larry I. Moatz [22] Flled: 1968 Attorney, Agent, or FirmBrumbaugh, Graves, 211 App]. No.2 774,527 Donohue & Raymond 57 ABSTRACT [30] Foreign Application Priority Data 1 n 1967 Swed n [6125/67 New dlalkylammoacylamhdes substituted with a haloc gen atom lll the dialkylamino group are disclosed 52 us. Cl 260/562 N; 260/562 B; 424 324 whch are as anesthems' [511 Int. Cl. C07c 103/50 5 Claim-5,1 Drawings HALOGEN SUBSTITUTED DIALKYLAMINOACYLANILIDES The present invention relates to halogen substituted dialkylamino acylanilides and their salts and also a process for their preparation'as well as pharmaceutical preparations thereof. the therapeutic use of such substances and pharmaceutical compositions containing at least one of these new compounds.

More particularly the present invention relates to new compounds of the formula wherein R. R and R may be the same or different and each represents a hydrogen or halogen atom, or an alkyl or alltoxy group of at most 3 carbon atoms including isopropyl provided that at most two of R. R and R are hydrogen atoms; R is methyl or ethyl. R is a straight or branched alkylene radical with from 2 to 6 and preferably 4 to 6 carbon atoms; A is a straight or branched alkylene radical having from 1 to 3 carbon atoms: X is a halogen atom selected from the class consisting of chlorine. bromine. and iodine; and therapeutically acceptable salts thereof. a process for their preparation. pharmaceutical compositions containing such compounds. and their use as local anesthetics.

Illustrative examples of compounds of the present invention are the following: N-methyl-N-[3'- chloropropyllaminoaceto-Z.o-xylidide. N-methyl-N- [5'-bromopentyl]aminoaceto-2.6-xylidide. N-ethyl-N- [2 -chloropropyl ]B-aminopropio-2.6-xylidide. methyl-N-[4'-chlorobutyl1aminoaceto-o-chloroanilide N-methyl-N-l5'-chloropentyllaminoaceto-oethylanilide. N-methyl-N-[S'-chloropentyl- 1aminoaceto-o-propylanilide. N-methyl-N-[4- chlorobutyl]aminoaceto-p-toluidide. N-methyl-N-[4-- -chlorobutyl ]aminoaceto-2-chloro-6-methylanilide and N-methyl-N-[ 5 '-ch|oropentyllaminoaceto-omethoxy'anilide.

The acid addition salts of the compounds according to the present invention are valuable local anesthetics and they are in particular usefulas long-acting local anesthetics. One possible explanation to this surprising and very useful property may be that these substances penetrate in the body tissues and are transported to the nervous membranes in the tertiary amine form where-' cyclizes to the formation of a N-heterocyclic quaternary ammonitim compound which is not easily removed from the nervous cell membrane.

The compounds of the present invention are prepared by reacting a compound of the formula wherein R. R R, R", R and A have the same meaning as above and Z is a member of the group consisting of hydroxy and acyloxy having not more than 6 carbon atoms. with a halogenating agent. such as a thionyl halogenide or a hydrohalogenic acid, during which reaction or in close connection thereto the compound of the formula I thus formed is converted to the desired therapeutically acceptable salt by reaction with the appropriate acid or transformed to such a salt by metathesis in a suitable solvent.

The expression therapeutically acceptable salt" is recognized in the art as an acid addition salt. which is physiologically innocuous when administered in a dosage and dose interval (e.g. frequency of administration) that is effective for the indicated therapeutic use of the parent compound. Typical therapeutically acceptable acid addition salts of the compounds of formula I include but a're not limited to the salts of mineral .acids. such as hydrochloric. hydrobromid. phosphoric or sulphuric acid. or organic acids such as lactic. levulinic. citric. fumaric. maleic. succinic. tartaric. benzoic acid and sulphonie, acids. such as methane sulphonic acid and sulpha'micacid.

Starting material of the formula ll may be prepared by either of the following two methods:

NH-CO-A-N 1 QM co A -.NH 2 R i l When using method B in some cases a cyclization of the halogen alcohol compound will occur and in such cases preferably a compound wherein Z is an acyloxy group should be used. Chloro pentanol for instance readily cyclizes to tetrahydropyran and instead an ester such as chloropentanol acetate should be chosen for the reaction. The acyloxy group can easily be removed by transesterification with for instance methanol or the acyl compound may be directly halogenated to the corresponding halogen derivative. For a further understanding of this invention references may be given to the following examples.

Example 1. Preparation of N-alkyl-N-[hydroxyalkyllaminoacylanilides used as starting materials.

Method A. N-Methyl-N-[4'-hydroxybutyl]aminoaceto-2.6- xylidide.

A mixture of 'chloroaceto-2.6-xylidide. N-

methylaminobutanol and triethylamine. 0.1 mole of each in 250 ml of benzene, was refluxed for 5 hours. After cooling the reaction mixture was treated with water. the benzene layer separated and the aqueous layer extracted once with ether. The combined. organic solutions were dried over potassium carbonate. The product was isolated as hydrochloride. m.p. l62-4-.5C (from ethanol/ethyl acetate). Yield 48%.

Calculated: Equivalent weight: Found: Equivalent weight:

Analyses: N 9.32 N 9.17 7:.

'N-Methyl-N-[6'-hydroxyhexyl]aminoaceto-2,6- xylidide was prepared in the same way using N- methylaminohexanol. Yield 47% of free base. b 160-70C.

Calculated: Found:

Equivalent weight: Equivalent weight:

B-(N-Methyl-N-[4-hydroxybutyl]amino)-propio- 2.6-xylidide and ,B-(N-ethyl-N-[2- hydroxyethyl]amino)-propio-2,6-xylidide were prepared in the same way from B-chloropropio-2.6- xylidide and N-methylaminobutanol respectively N- ethylaminoethanol. These compounds readily decompose at distillation and the crude products were used for the next step without purification.

-'r nalogen R Z Calculated: Found:

Equivalent weight: Equivalent weight:

N-Methyl-N-[S'-acetoxypentyl]aminoaceto-2,6- xylidide was prepared in the same way from chloropentylacetate and methylamino aceto-2,6-xylidide. Yield 31% of product, biog 185C, n,,- 1.5148.

Calculated: Found:

Equivalent weight:

8.76 "/1. Equivalent weight: 8.78 "/1.

N-Methyl-N-[ 5 '-hydroxypentyl laminoaceto-Z .6- xylidide.

A solution of 10 g (0.031 mole) of the acetyl com pound and 7.6 g (0.040 mole) of p-toluenesulphonic acid monohydrate in m1 of absolute alcohol was refluxed for 15 hours. The solvent was evaporated, the residue dissolved in water and this solution made slightly alkaline. The base was extracted repeatedly with ether. the extracts dried over MgSO. and distilled. yield 5.5 g (63.5%) of oil. b 171-3C, n,,'- 1.5292.

Calculated: N 10.05%; Found N 10.0%.

Example 2. Conversion of the aminoalcohols to corresponding chloro compounds.

A mixture of 0.015 mole of the hydrochloride of the aminoalcohol and 0.030 mole of thionylchloride in 100 ml of chloroform was refluxed for 20 hours whereupon the solvent was evaporated. Usually the residual hydrochloride was directly recrystallized. ln two cases it was found more suitable to purify the product as free base.

Compounds prepared in analogous way and represented by the formula .5 6 good frequency of block and in particular a long duration of action.

NH CO (Cl-l N In thefollowing Table 2 some of the compounds of m (OH the present invention are compared with lidocaine and 01-1 2 11 tetracaine according to accepted methods for testing excitation block in vitro and in vivo and toxicity. The are listed in the following Table 1. compounds tested are represented by the formula Table l R m n Yield M.P.C Solvent for Formula Analyses "/1 recryst. C alc. Found Equiv. N 7: Equiv. N

CH 1 2 62 65.5-7 light petrol C H N ocl 1.4.8 11.0 257 11.0 CH; 1 3 63.5 ll5.5-7.5 ligroin H ,N. .OCl 268.8 10.43 270 10.4 CH 1 4 67 149-52 acetonitrile C, H. ,;,N. ,OCl 319.3 8.78 308 8.53

X HCl CH 1 5 75 142-4 5 methyl-iso- C H N OCl 333.3 8.41 332 8 butylketone X HCI CH 1 a 92 140-3 methylpropyl- C,,H ,N. .OC1 347.3 8.07 349 8.00

ketone HCI CH: 2 4 l2" l203 methyl-iso- C H. .,,N.;OC1 333.3 8.41 331 8.47

butylketone X HCI 2H5 1 2 75 152(d) pentanone-Z C, H ,,N. ,OCl 305.3 9.18 310 9 12 x HCI H, 2 7 13' 158-60 acetonitrile C H N- oCl 319.3 8.78 321 8.62

. x HCl "mer all yield. computation based on starting material of stage A.

In analogous way the maleate of N-methyl-N-[5- chloropentyllaminoaceto-o-methoxyanilide was prepared. After recrystallization from ethyl acetate the H N product melted at 85-88C. Calculated equiv. weight Y 7 2'; 414.9. N 6.75%; found equiv. weight 417. N 6.8171. 2

Example 3.

Table 2 m R R lntravenous Blocking effect Remarks toxicity LD in mg free Isolated frog Guinea-pig base per kg body sciatic nerve" sciatic weight (mouse) nerve block ReLeff. Rel in vivo at 5 min. duration (relative duration) 6 1.() 1.0 l.0 Tetracaine standard long action anesthetic A. Mauro. A.P. Truant and EL. M4: Cawle). Yale J. Biol. Med. 21 (19-18) 113.

N-methyl-N-[ 5 '-bromopentyl laminoaceto-2.6- xylidide.

5.6 g of N-methyl-N-[S'-acetoxypenty1laminoaceto- 2,6-xylidide were dissolved in 150 m1 of glacial acetic acid containing 30 g of hydrogen bromide and the mixture left at 90C for 24 hours. Another 30 g of dry hydrogen bromide was passed into the solution and the heating continued at 90C for 24 hours more. The solvent was evaporated and the crystalline residue treated with acetone. The bromo-compound was sucked off and washed with ether. Yield 6 g with m.p. 154158C. Two recrystallisations from pentanone-3 raised the m.p. to 158.5-l C. Calculated Br 37.8%; Found Br 37.5%.

The compounds of the instant invention display excellent local anesthetic properties such as rapid onset,

The compound N-methyl-N-[S'-ch1oropentyl]- aminoaceto-o-methoxyanilide was tested using the same methods and with the following results.

Blocking effect The agents were found to compare very well with the known compounds tetracaine and lidocaine. The

INH-

wherein each of R, R and R is selected from the group consisting of hydrogen halogen, alkyl of at most 3 carbon atoms. including isopropyl and alkoxy having not more than 3 carbon atoms. including isopropoxy. provided that at most two of R. R and R" are hydrogen atoms; R" means methyl or ethyl; R is an alkylene radical with from 2 to 6, and preferably from 4 to 6. carbon atoms which may be branched; X is a halogen atom from the class consisting of chlorine. bromine. and iodine; and A is a member of the group consisting of straight and branched alkylene radicals having from I to 3 carbon atoms; and therapeutically accetable salts thereof.

2. A compound according to claim 1 of the formula wherein m is an integer from 1 to 2 inclusive; n is an integer from 2 to 6 inclusive; and R is selected from I the class consisting of methyl and ethyl. 3. The compound I\'H.CO.CH .N

, cH ct 4. The compound NH. CO. CH N (CH Br 5. A member selected from the group consisting of a compound of the formula wherein m is an integer from 1 to 2 inclusive; :1 is an integer from 2 to 6 inclusive; and R is selected from the class consisting of methyl and ethyl; and the therapeutically acceptable salts thereof. 

1. A MEMBER SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS OF THE FORMULA
 2. A compound according to claim 1 of the formula
 3. The compound
 4. The compound
 5. A member selected from the group consisting of a compound of the formula 